SoftBank shares sink after AI slowdown calls hit its $64.6B OpenAI bet

SoftBank Group shares plunged as much as 13% in Tokyo trading on Monday, their steepest drop in nearly three months, after the CEOs of both Anthropic and OpenAI called for slowing the pace of artificial intelligence development and OpenAI's Sam Altman ruled out a 2026 initial public offering.

The selloff, which left the stock unable to trade for the first 19 minutes of Monday's session due to a flood of sell orders, strikes at the heart of SoftBank's strategy. The Japanese conglomerate has committed $64.6 billion to OpenAI, and the value of that bet hinges on the AI company's growth trajectory and eventual public listing.

The Weekend That Rattled Investors

The catalyst arrived over the weekend. On Saturday, Anthropic CEO Dario Amodei published a 3,800-word essay titled "We Must Pace the Frontier," proposing a three-step plan to temper the speed of AI advancement. His proposals included embedding independent monitors inside AI labs, coordinating safety standards among companies in democratic countries, and pursuing global regulation.nytimes+3

Hours later, Altman posted that he agreed with Amodei. "I agree with Dario that we need to pace the frontier," Altman wrote, adding that the topic "has been a primary topic of discussions we've had at OpenAI in recent weeks," according to TechCrunch. Google DeepMind's Demis Hassabis also expressed agreement, according to the New York Times.techcrunch+1

Separately, in an interview with Fortune published Saturday, Altman said OpenAI would not go public this year. "I actually think that, given everything happening with safety, right now would be an ill-advised moment to go public," Altman said. When pressed on timing, he added: "I would say not 2026".engadget+2

SoftBank's Concentrated Exposure

When trading opened in Tokyo on Monday, SoftBank shares gapped lower, opening at 5,926 yen — down 9.4% from Friday's close of 6,540 yen — before falling as low as 5,720 yen. Bloomberg reported the decline reached 13%, the steepest since a similar drop on June 26 when earlier reports of an OpenAI IPO delay surfaced.bloomberg+1

The damage was concentrated. TSMC Taiwan Semiconductor Manufacturing Company Limited ↗ 6.33% fell just 1%, while SK hynix ↗ 2.78% dropped about 6% in Seoul and Kioxia lost 7.2% in Tokyo. The gap reflects that SoftBank's valuation is uniquely tied to OpenAI's prospects rather than broad AI hardware demand.techi

The IPO delay is particularly consequential because SoftBank's newest OpenAI shares are preferred stock that converts to common shares only upon a public listing, leaving the company holding a large private stake with no clear liquidity event on the horizon.techi

Financing Pressures Loom

The market turbulence arrives at an awkward moment for SoftBank's balance sheet. The company is set to repay $25.9 billion on Tuesday — the remaining balance of a $40 billion bridge loan used to fund its OpenAI investment — ahead of its March 2027 maturity. Its final $10 billion tranche payment to OpenAI is due October 1.bloomberg+2

SoftBank separately secured an $11.87 billion loan to support the OpenAI investment, exceeding its original $10 billion target, according to a report citing sources familiar with the deal. The company is also holding investor meetings in New York this week to gauge appetite for a potential $10 billion to $20 billion junk-bond sale.techflowpost+2

Whether Monday's selloff proves a temporary shock or a lasting repricing may depend on how concretely OpenAI and its peers define "pacing the frontier" — and whether SoftBank can refinance its debt stack smoothly while its largest investment remains private and its growth outlook newly uncertain.